KLH model 9 electrostatic Speakers

I just bought the above speakers, I like them a a lot , I am thinking if it’s possible to replace the power cord on the power supplies. On this speakers? Thanks B
Many manufacturers makes C7 power cords. Wireworld, Cullen, Pangea to name a few. I would check those out and see if you find anything you like. 
Additionally some cable manufacturers like Triode Wire Labs will make custom power cables for you. 
David JansZen rebuilds and sells them in Columbus, OH. They were designed by his father. He can answer any question.

If you just need a C7 I have and like a WireWorld.
I have owned a pair of KLH Nines since 1992. There is absolutely NO benefit to replacing the stock power cords - contrary to what the neurotically obsessed will claim! The power supplies are low-current and adequately designed! Their sound starts there! Not from the power cord to the wall AC outlet!
+1 Jason
I would never dream of replacing the wall warts for my Acoustats. That would be like putting a LPS into an UltraCap.
Right, there is little to no current drain for an ESL bias supply, just high voltage. Power cords make no difference. The bias supply can actually drift up to 10% and you probably would never hear it. I can decrease the power by 500 volts and you can not hear a thing. 

KLH 9's like Quads are very intimate speakers in spite of their size. They sound best close in and close together. The 9's are certainly more reliable. But they are touchy speakers to set up right as the high frequency balance evolves as you go off axis or change height. You set them to sound right at the listening position which is the best you can do.
Acoustats were the first ESLs that had reasonable dispersion and were truly indestructible. As they evolved into the 8 foot tall "plus" models things got really serious. Now you have full range line sources capable of projecting more sound into a room with much less distortion than any dynamic loudspeaker that was not itself a line source. Sound Labs further refined the ESL giving it a perfectly even dispersion pattern over 45 degrees and even more detailed imaging. 

Having used ESLs with occasional interludes with planar magnetic and ribbon speakers since 1978, I have return permanently to ESLs. IMHO nothing trumps a line source ESL. It is the loudspeaker with which you are most likely to achieve the absolute sound. As JGH said back in the 60's with the Model 9 you don't listen to the loudspeaker. You listen through it. I think that applies to all decent full range ESLs. I close my eyes and I don't hear loudspeakers any more., they disappear. 
I love KLH 9's. I did notice an improvement upgrading the power cords to twisted silver over copper conductors with braided shield for the ground connections. Replace ALL rectifiers and capacitors. Rectifiers should be high speed silicon variety. Check and upgrade all connections points, silver or gold. These are 50+ years old most likely. They sound fantastic even compared to newest technology.
Mijostyn, it blew me away the KHL 9 diasappear, yes , it’s all music, no speakers.Very dynamic.This KHL 9 are own by The late Dr Close, they are in very good shape, He modified the power supplies.The sons are so nice to deal with.
Fiesta 75 , when I have my Martin Logan request , MIT z cord did improve the sound, and a regular Kimber pc , also did improved it, Can I just use an ordinary 2 prong pc? 
Fiesta 75 I have Viva integrated 17 w , I use to used this amp on my Andrea Eggleston 87!db speakers on low level volume, can I try to use it on my KHL 9 speakers too?
Fiesta Viva 300p is just doing fine on the nines, lovely music is coming out of the nines, the volume is set Between 9 and 10.
The type of power cord will not effect the sound. It is only there to charge the electrostatic panel. Don’t call David Janszen and ask him about it, he will laugh at you. I own the Janszen zA2.1 speakers.
I used a 25 watt PP tube amp with my KLH Nines successfully! Now have a Futterman H3 25 wpc OTL tube amp!
Jason , Gordon Holt power requirements recommendations is between 35 w and 75 w, my viva is 17w, ok on low volume, my art audio is 40 w this tube amp gives me more dynamic, extensions and nice bass and slam, Gondon is right.
There is absolutely NO benefit to replacing the stock power cords - contrary to what the neurotically obsessed will claim!
So true, replacing power cords will do sweet *.* to the sound.
As the current draw is so miniscule even a AC plug packs were enough to power the later Accustats ESL's

Cheers George
So far on cables I get Just a little bit improvement, with the nines do make big changes on every amps  I tried.

KLH model 9 electrostatic Speakers
I am thinking if it’s possible to replace the power cord on the power supplies.

Changing power cords on ESL’s power supplies will do nothing whatsoever for the sound.
As rubbing a piece of plastic with a cloth is almost enough to power/charge them😉

Cheers George
The Cerious Technology Speaker Cable made the KLH bring more music, I noticed the panel are more filled with music info.The bass is much full firm .
The KLH 9 And Cerious Technology Speaker Cable are match made made in heave, Lance I will call David on this.
@jayctoy , ESL have always been amp sensitive (not power cord senstive) They are also a very reactive load and their impedance drops dramatically as the frequency goes up. By 20K they can be under 1 ohm.
This has destroyed many amps. Current demands increase with frequency. Many amps will overheat because of this. 
Back when JGH was reviewing the KLH 9's there were very few if ant high powered amps. Amps like the Crown 150 and Phase Linear 700 would overheat and self destruct. The best amps to use back then were the Marantz Model 9's and several Mcintosh amps. Today You would use a High power Class A amp with a lot of heat sink or an Atma-Sphere amp.
M60's would be perfect!
Mijostyn my Plinius sa 100 has no problem powering the nines. I get all the dynamics and musicality of the nines, my Norh monos sounds good on the Nines.How much power is the atmasphere  M60?
Today You would use a High power Class A amp with a lot of heat sink or an Atma-Sphere amp.
M60's would be perfect!

How much power is the atmasphere  M60?


While the power of the M-60 is fine (about 60 to 80 watts) the high frequency impedance will cause the amp to sound rolled off, which it is not. To solve this a set of ZEROs (www.zeroimpedance.com) should be employed. With the ZEROs the M-60s will make more like 80 watts.

Ralph thank you for your response, I checked the zeroimpedance unit $1149 a pair. 
Ralph it looks like my Art Audio concierto 40 w will be benefited from the Zero impedance, I think the KLH need to be using 16 ohm.Thanks again...
Ralph, why not just put 200 watt 2 ohm resistors in series with the speaker. Yes, they would absorb some power but they would cost only $40 dollars and I bet you would still get 60 Watts out of the M60's. The other thing is the roll off would be way up there and I doubt most of us could hear it?
Will Dynaco st 70 watt good enough power for the nines?
It will run them. But the amp, as good (as a refurbished one is) will be a bit outclassed. 
Yes, they would absorb some power but they would cost only $40 dollars and I bet you would still get 60 Watts out of the M60's. The other thing is the roll off would be way up there and I doubt most of us could hear it?

You can hear it. Its an interesting idea; if the power isn't an issue it might work.

"Will Dynaco st 70 watt good enough power for the nines?"

Depends on how loud you listen. I would love to hear the 9's with something like a Pass XA 60.8. Parasound JC 1+ would be overkill. 
I am not familiar with the Plinius amp but if it sound fine stick with it. It is a 100 watt/ch Class A amp which in my experience should be more than enough. If it sounds anything like my old Krell KMA 100's you should be in hog heaven.
I tried my MIT Speaker Cable with a box , I think it’s the s3 , there is no sound coming out from KLH.
I connected my MIT speaker cables with a box to my KLH , no sound came out. The mit works on my other non electrostatic speakers, I wonder why..
I agree mijostyn! After many years with cones and domes planar magnetic the ESL treble is most like live instruments. Trumpet, violin, saxophone etc. I recently picked up the motion ESL by Martin Logan at a great price. Even that little speaker has truth of timbre a $100k speaker couldn't match. I know ML it's not perfect ( slightly lean sound) but what it does well is SOTA!
Martin Logan Speakers are excellent, I have the request for five yrs, this speakers like bass trap on the outer side.

Glad to have found this thread. I've owned KLH Nines since 1972 and driven them with Futtermans H3a and Marantz Model 9 I am still driving the KLH Nines with the same Futterman (recapped of course) and of the 3 pairs I've owned I've kept one and had it refurbished by David Janszen. I donated an early prototype (used 4 large bass panels instead of the 10 now used) I had as well to David as a gift. I drive the Nines with the Futterman or Accuphase. I've heard just about every Hi End speaker made since I love going to audio shows and owned Sound-labs A-3s and as well as still owning Modified zA2.1. Once you listen to a Nine its hard to forget them. The cords to the power supply cans make no difference at all.

@rdiiorio , you have been at it for a while! Most people back then though the SOTA was Marantz Model 9s driving K horns. If you were volume centric it was but if you cared about realism the KLH 9's were it. The only fly in the ointment is that the KLH 9's are not capable of realistic output and bass. It is hard to recreate the visceral side of music. ESLs do not project power well until they become full range line sources. The panels have to extend from floor to ceiling without gaps. Add subwoofers to such a speaker and what you get is the nuance of an ESL with the power and controlled directivity of a large horn. Currently only Sound Labs makes such a loudspeaker and it is darn impressive. 

Like rdiiorio, I've owned a couple of pairs of KLH9s since the early '70s. I worked in a high end store in Berkeley where a single pair of 9s could be heard powered by Marantz 9s, a hard combination to forget. The room--always critical to ESL setup--was well matched.  There was good bass to about 40Hz.  In bigger rooms, more 9s or subwoofers like the better RELs do the trick. The very low impedance of the 9s at low frequencies has always been a problem.  With one pair of custom built OTL amps which liked high impedance , series hookups of the 9s worked amazingly well.  The same hookup damaged another type of OTL.  Never a problem with transformer coupled tube amps like the Marantz 9s.  For a number of the early, fragile solid state amps, an RC network in series to roll off the very low frequencies gave protection.
Of all the speakers I've owned over the past 60 years, including Quads, Infinity Servo-Statiks, et. al., none has come close to optimally set up KLH9s.  Charlie Hansen of Ayre agreed.

Here is a link to an early pair of KLH model Nines showing a wholly different design in the amount of transducers used 5 verses 11, with 11 being used in final production units by KLH


Having owned the Sound-Lab A-3 I found using one segmented diaphragm to reproduce all frequencies was not as fast or natural sounding as compared to 2 or 3 pairs of KLH model Nine (series/parallel) driven by a Futterman, augmented with JBL B360/BX63A Sub/xover driven by a  McIntosh amp. Volume levels easily exceed 100db